There have been demands for an objective lens drive which drives an objective lens, which condenses light on a recording surface of an optical disk, in a tilting direction of the optical axis of the objective lens in addition to the optical axis direction and a direction perpendicular to the optical axis in order to correct optical coma aberration in an apparatus for optical disks having higher density. For example, Patent document 1 (Japanese Patent Laid-Open No. 2001-93177) discloses such an objective lens drive. The prior art disclosed in Patent document 1 will be taken as an example below to describe a conventional objective lens drive in accordance with the accompanying drawings.
FIG. 3 is a perspective view showing the conventional objective lens drive. A movable part of the objective lens drive is constituted of an objective lens 31 for condensing a light beam on an optical disk, a lens holder 32 for holding the objective lens, and three coils 33 for driving the objective lens in the optical axis direction, a direction perpendicular to the optical axis, and a tilting direction of the optical axis. The movable part has one end fixed on a fixing part 35 via six elastic support members 34 which elastically support the movable part. Current is applied from the six elastic support members 34 to the three coils 33 to operate the movable part in the optical axis direction, the direction perpendicular to the optical axis direction, and the tilting direction of the optical axis.
In the apparatus for optical disks, in order to position light, which has been condensed by the objective lens, in the optical axis direction, the direction perpendicular to the optical axis, and the tilting direction of the optical axis with high accuracy and low power consumption, there have been demands for higher operating sensitivity in all the directions in the objective lens drive.
In order to improve the static operating sensitivity in the optical axis, the direction perpendicular to the optical axis direction, and the tilting direction of the optical axis, it is necessary to increase the thrust of the objective lens drive by increasing the efficiency of a magnetic circuit and to reduce the spring constant of the support member.
However, according to the contents disclosed in Patent document 1, the movable part is elastically supported by the six linear elastic support members and thus the operating sensitivity is not necessarily improved to a sufficient level. Further, since the movable part is supported by the six linear elastic support members, excessive restraint makes the operation of the movable part unstable.
Moreover, in the case where a coil-shaped part or a bent part is provided on a part of at least two of the six elastic support members, the operating sensitivity is improved and the excessive restraint is eliminated. However, two of the six support members have different shapes and thus the cost is increased by a larger number of assembling steps and more complicated operations.
The present invention is devised to solve this problem and its object is to provide an objective lens drive which improves operating sensitivity and assembling workability when driving and controlling light, which has been condensed by an objective lens, in the optical axis direction, a direction perpendicular to the optical axis, and a tilting direction of the optical axis.